Lap roll pressure means for lapping machines



LAP ROLL PRESSURE MEANS FOR LAPPING MACHINES Filed Sept. 28-, 1956 June 1959 J. R. LONG E'IV'AL 5 Sheets-Sheet 1 Commas-55011 INVENTORS'. 0 HN \2. Lone 2nd ALDEN GFu m:

ATTORNEYfi 2,890,841 LAP ROLL PRESSURE MEANS FOR LAPPING MACHINES Filed Sept. 28 1956 June 1959 R.'LONG ETAL INVENTORS'. JOHN 12. LONC: and Amen C. FuNT.

grill, {Au-ad?- 5 Sheets-Sheet 2 ATTORNEYS June 1959 J. R. LONG ETAL 2,890,841

LAP ROLL PRESSURE MEANS FOR LAPPING MACHINES Filed Sept. 28, 1956 3 Sheets-Sheet 3 INVENTORSI ToHN R. Lone. and I ALDEN C. FLINT BY 59L, @291, fl d-i- ATTORNEYS 4 United States Patent LAP ROLL PRESSURE MEANS FOR LAPPING MACHINES Application September 28, 1956, Serial No. 612,728 6 Claims. (CL 242--55.1)

This invention relates to improved means for applying pressure to opposite ends of the usual lap pin or lap roll associated with sliver lap and ribbon lap machines and is particularly concerned with improvements in apparatus of the character described in the copending application of John R. Long, Serial Number 327,796, filed December 24, 1952, for Head Block for Lapping Machines, and now abandoned.

The apparatus disclosed in said copending application is particularly devised for use with picker machines and comprises a pair of double-acting cylinders Whose piston rods have head blocks attached thereto which are movable into and out of engagement with opposite ends of a lap pin on which a lap roll is wound. Picker machines are provided with means to automatically release a knock-oil? or operating lever upon a predetermined amount of compressed textile fibers being wound on the lap pin. The apparatus disclosed in said copending application also includes a four-Way valve which is actuated upon the operating lever moving to inoperative position for causing fluid pressure to flow to the lower ends of the cylinders to raise the head blocks out of engagement with the lap pin. Conversely, as the operating lever is moved to operative position, fluid pressure flows to the upper ends of the double-acting cylinders, which cylinders are disposed above opposite ends of the lap pin, and thus, downward pressure is applied to the piston rod and the head blocks to cause the same to engage opposite ends of and apply pressure to the lap pin.

It is an object of this invention to provide an apparatus similar to that disclosed in said copending application, but which is particularly devised for use with lapping machines of the type known as ribbon lap or sliver lap machines, wherein the lap roll is formed between a pair of flanges or disks through which the lap pin extends, with opposite ends of the lap pin being journaled in bearmitted to the relay valve unit by the pilot valve unit is over-ridden so pressure is again admitted to the upper ends of the double-acting cylinders so that, when the knock-off latch is returned to operative position to release the pilot valve unit, manual pressure may be removed from the core of the second or relay valve unit and fluid pressure will then continue to be, applied to the upper ends of the double-acting cylinders until the knockolf latch again moves to inoperative position.

Some of the objects of the invention having been stated, other objects will appear as the description pro ceeds when taken in connection with the accompanying drawings, in Which-- Figure 1 is a plan view of a portion of a ribbon lap machine with the improved lap pin pressure means mounted thereon;

Figure 2 is a fragmentary side elevation looking at the upper side of Figure 1;

Figure 3 is a view looking at the opposite side ofthe portion of the machine shown in Figure 2;

Figure 4 is a discharge end view looking at the lefthand side of Figures 1 and 2 and at the right-hand side of Figure 3;

Figure 5 is an enlarged fragmentary vertical sectional view taken substantially along line 5-5 in Figure 4;

Figure 6 is, a transverse vertical sectional View taken along line 6-6 in Figure 2;

Figure 7 is a schematic view of the fluid pressure circuit for controlling the improved pressure applying means.

The conventional means for driving the lap roll and for mounting the lap pins are practically or substantially the same on both ribbon lap and sliver lap machines and, accordingly, the machine shown in the accompanying drawings will be referred to as a ribbon lap machine and the term ribbon lap machine is also meant to include a sliver lap machine.

As is well known in the art, the function of a ribbon lap machine is to prepare the laps for a comber so they will be subjected to a minimum waste in the combing operation. To this end, laps or lap rolls are usually formed by a sliver lap machine and are placed upon stack rolls Which deliver slivers to top and bottom drafting rolls which draft and parallel the fibers. Portions of the Webs from two sets of such drafting rolls are illustrated in Figure l, which webs are commonly known as ribbons ings guided for vertical movement in the frame of the machine, the piston rods of double-acting cylinders being connected, at their lower ends, to the corresponding bearing blocks.

It is another object of this invention to provide apparatus of the character described wherein a pilot valve unit is provided which is normally spaced from a conventional knock-off lever or latch of a lapping machine of the character described and wherein, upon a lap roll of predetermined diameter being Wound on the lap pin, the knockoff latch moves into engagement With and operates the pilot valve unit which, in turn, operates a second or main relay valve mechanism for reversing the flow of fluid from a fluid pressure system to the double-acting cylinders to thereby raise the bearing blocks with the lap pin to release the lap roll from pressure engagement With the take-up rolls on which it normally rests during operation of the machine. On the other hand, the relay valve unit is so constructed that, upon manual movement of its core, as effected by a foot pedal or other, means, the pressure ad- R and are carried over and beneath curved plates 10 which are arranged in the usual manner so they partially overlap each other and thereby form the various ribbons R into a common fibrous web indicated at W.

From the curved plates 10, the ribbons R and the Web W formed therefrom pass between calender rolls 12, 12a which are suitably journaled in opposite side frame members 13, 14 of a frame broadly designated at 15. The calender rolls 12, 12a are driven by a conventional gearing connected with a main shaft 16. This gearing includes a worm 17 fixed on the main drive shaft 16 which meshes with a Worm gear 20 (Figure 6) fixed on a shaft 19 journaled in the frame members 13 and 14.

As shown in Figure 6, a gear 21, of the same diameter as gear 20, is also fixed on theshaft 19 and meshes with a gear 22 fixed in coaxial relation to the lower calender roll 12 to drive the same. The other end of the lower calender roll 12 has a gear 23 fixed in coaxial relation thereto which meshes with a-gear 23a for driving the upper calender roll 12a. The calender rolls 12, 12a feed the web W onto a pair of relatively large lap supporting rolls 24, 25 to form a lap roll or lap 26 which is wound about a lap pin or shaft 27. The supporting rolls 24, 25 are fixed on respective transverse shafts 28, 29 having respective gears 30, 31 mounted on corresponding ends thereof (Figure 2) and the lattergears engage an idler gear 32 so the gear 30 fixed on the shaft 28 drives the front supporting roll 25. The end of the shaft 28 opposite from that on which the gear 30 is mounted has a relatively large gear 34 fixed thereon (Figure 3) which meshes with a relatively small gear or pinion 35 fixed on the shaft 19, adjacent the side frame member 13.

As best shown in Figure 7, the lap pin or shaft 27 is journaled in bearings 40, 41 carried by bearing blocks or guide blocks 42, 43, respectively. The guide blocks 42, 43 are guided for vertical movement in upstanding portions or standards 45, 46 carried by or formed inte gral with the side frame members 13, 14. In order to maintain the lap pin or shaft 27 in the bearing blocks during the winding of the lap roll 26 thereon, one end portion of the lap pin is provided with an enlarged threaded portion 44 thereon which is threaded into the corresponding bearing 41, and the extreme end of the shaft 27 adjacent the threaded portion 44 is provided with a hand wheel 27a to facilitate installation of and removal of the lap pin 27 from the bearing blocks 42, 43. The shaft or lap pin 27 also extends through disks or flanges 26a between which the lap roll 26 is wound.

In order to stop the machine when the lap roll 26 has reached predetermined size, the ribbon lap machine is provided with a rod or bar 50 whose upper end is attached to the bearing block 42 (Figure 3) and whose lower portion has an outwardly projecting pin or abutment 51 thereon which, in the course of upward movement of the bearing block 42, as effected by the gradually increasing diameter of the lap roll 26, engages the free end of a latch or knock-off arm 52 pivotally connected to a crank 53. The latch 52 normally engages a lug 55 fixed on a substantially L-shaped bracket carried by the side frame member 13 of the frame 15.

The latch 52 is normally maintained in lowered position; in engagement with the lug 55, by means of a tension spring 57, one end of which is connected to the free end of the latch 52 and the other end of which is connected to the side frame member 13, as at 58. The tension spring 57 also tends to urge the latch 52 to the left in Figure 3. It is thus seen that while the parts occupy the position shown in Figure 3, the latch 52 is normally restrained from movement from right to left. However, when the abutment 51 on the bar 50 is moved upwardly by the lap roll 26to where it engages and raises the latch 52, the latch 52 is elevated out of engagement with the lug 55 and the spring 57 will then pull the latch 52 from right to left in Figure 3. latch 52 is pivotally connected in Figure 3, is fixed to a rocker shaft 59 journaled in the side frame members 13, 14 of the frame and has, on its other end, an operating lever or hand lever 61 to which one end of a link 62 is connected. The link 62 extends freely through the machine and engages a switch S which, upon movement of the link 62 from left to right in Figure 2, stops the usual driving means for the ribbon lap machine.

The parts heretofore described are conventional and usual parts of a ribbon lap machine, with the exception that the bar 50 having the abutment 51 thereon is sub stituted for the rack usually employed on such machines for progressively raising the corresponding bearing block 42 as the web W is wound thereon to form the lap roll 26.

In order to apply predetermined, uniform pressure downward against the bearing blocks 42, 43 at all times during operation of the machine, and to raise the bearing blocks 42, 43 upon actuation of the stop motion of the machinein the manner heretofore described, an improved pressure-applying apparatus is provided which comprises a pair of double-acting cylinders 65, 66 which may be either air cylinders or hydraulic cylinders and are shown as being air'cylinders in the present instance. The upper and lower ends of each of the cylinders .65, 66. are closed and the lower ends thereof .are'supported on respective The crank 53, to which the V 4 inverted substantially U-shaped brackets 67, 68 which are fixed to the upstanding portions 45, 46 of the respective side frame members 13, 14 in which the bearing blocks 42, 43 are guided for vertical movement.

Each of the cylinders '65, '66 has a piston 69 mounted for vertical sliding movement therein, to the lower end of which the upper end of a pistonrod or ram 70 is suitably secured. The piston rods 70 extend downwardly, slidably penetrate the bottoms of the respective cylinders and loosely penetrate the upper horizontal portions of the brackets or standards 67, 68. The piston rods 70 are pivotally connected to the corresponding bearing blocks 42, 43 as by clevises 71 each of which is penetrated by a pivot pin 72 carried by a pivot block 73, there being one of the pivot blocks 73 fixed to the upper surface of each of the bearing blocks 42, .43.

As best shown in Figures 1, 2, 3, 5 and 7, corresponding ends of pipes or conduits 75, 76 are communicatively connected to the closed upper ends of the respective cylinders 65, 66 and corresponding ends of pipes or conduits 80, 81 are communicatively connected to the closed lower ends of the respective cylinders 65, 66. The ends of the conduits 75, 76 remote from the cylinders 65, 66 are connected to a common pipe of conduit 82 by means of a pipe T 83. The ends of the conduits 80, 81 remote from the respective cylinders 65, 66 are connected to a common pipe or conduit 84 by means of a pipe T 85.

The conduits 82, 84 are connected to a relay valve unit broadly designated at 86, such as is manufactured'by Westinghouse Air Brake Company, Wilmerding, Pennsylvania and which is described by said company as a type D Pilotair valve. The relay valve unit 86 comprises a main substantiallytubular body or housing '87 which is divided into a plurality of co-axial compartments or chambers a to e, inclusive, by means of a plurality of resilient partitions, each of which is indicated at 90. Each of the partitions 90 is provided with a hole 91 therethrough. The holes 91 are adapted to receive corsponding longitudinally spaced enlarged portions 1'' to i, inclusive, of a valve core or plunger 95.

The plunger 95 extends out of opposite ends of the tubular housing 86 and one end thereof is connected, by means of links 96, to a foot pedal or treadle 97 (Figure 2) which is pivotally connected to the corresponding end of the housing 86, as at 100. The other end of the plunger or core 95 is connected to a relay piston 101 mounted in a relatively small cylinder 104 and which piston is normally urged away from the housing 86 by a compression spring 103.

The piston is mounted for axial sliding movement in the relay cylinder 104 fixed to the corresponding end of the housing 86 and to whose end remote from the housing 86 a conduit or pipe 105 is communicatively connected. The other end of the conduit 105 is connected to a pilot valve unit 106 for communication with a chamber 107 in the housing of the valve unit 106. The housing of valve unit 106 is also provided with p a chamber 110 which is defined by a restriction 111 in a medial portion of the housing of valve unit 106 and which valve seat is normally engaged by a check valve 112. The check valve 112 is normally urged to closed position against its seat 111 by a compression spring 113 positioned in the chamber 110. A compression spring 114 in the chamber 107 normally urges a tubular valve plunger 115 away from the check valve 112 and a reduced outer portion of the valve plunger 115 is positioned in alinement with and above the latch 52. The pilot valve unit 106 is suitably secured to the frame 15 of the ribbon lap machine. A pipe or conduit is connected to the housing of pilot valve unit 106 for communication with chamber 110 and leads to a medial portion of a conduit or pipe 121, one end of which is connected to the housing 87 of the relay valve unit 86 for communication with the chamber c, and the other end of which is connected to a suitable source of fluid pressure which is shown schematically as a compressor 122 in Figure 6.

A pressure-regulating valve 123 is interposed in conduit 121 between the compressor and conduit 120for predetermining the pressure admitted to cylinders 65, 66 and the pilot valve unit 106. It will be noted that the conduits 82, 84 communicate with the respective chambers d and b in the housing 87 of the relay valve unit 86. The housing 87 is also provided with a pair of exhaust ports 124, 125 which communicate with the respective chambers a and e.

Method of operation In starting the machine, the lap pin 27 is. positioned in the bearings 40, 41 and through the disks 26a and the free end of the web W is wrapped around the lap pin 27 by the operator in the usual manner. Assuming that the pistons 69, piston rods 70 and bearing blocks 42, 43 are in raised position, the foot pedal 97 (Figure 2) is depressed and the operating lever 61 moved to operative position so the parts occupy the positions shown throughout the drawings, with particular reference to Figure 7. However, since the lap roll 26 is just being started, the bearing blocks 42, 43 and the lap pin 27 will occupy a substantially lower position than that illustrated in the drawings relative to the frame 15.

Now, as the lap roll 26 builds up to the desired diameter, the abutment 51 on the bar 50 (Figure 3) moves upwardly, engages and raises the latch 52 out of engagement with the lug 55 to stop the machine in the manner heretofore described. In so doing, the latch 52 engages the lower end of the plunger 115 (Figure 7) and moves the same into engagement with the check valve 112 to move the same off the seat 111, whereupon compressed air or fluid under pressure flows from the compressor 122 through the conduits 121, 120, through the pilot valve unit 106 and the conduit 105 to the cylinder 104 of the relay valve assembly.

In so doing, fluid pressure causes the piston 101 to move from right to left in Figure 7, thus moving the plunger 95 therewith so the enlarged portions g and h thereof move out of engagement with the resilient partitions between chambers b, c and d, e, respectively, and into engagement with the partitions between the chambers a, b and c, d, respectively. Thus, fluid pressure flows from pipe 121 through chambers c, b and, thus, through the conduits 84, 80 and 81 to the lower ends of the cylinders 65; 66 to raise thecorresponding bearing blocks 42, 43 and to thereby raise the lap roll 26 out of engagement with the supporting rolls 24, 25.

At the same time, compressed air or fluid pressure is exhausted from the upper ends of the cylinder 65, 66 through the respective conduits75, 76 and conduit 82 and through the chambers d, e in the body 87 of the relay valve unit 86 to be exhausted through the port 125. It is thus seen that, each time the machine is stopped, the lap roll 26 is automatically raised entirely out of engagement with the supporting rollers 24, 25 so the lap pin 27 may easily be removed from engagement therewith. It is apparent that the machine may be stopped as desired simply by manually raising the latch 52 to release the same from engagement with the lug 55.

Now, when the machine is started, the operating lever or handle 61 is moved, manually, to'operative position, in the course of which the latch 52 (Figure 3) drops as the notch therein engages the lug 55 so the springs 113, 114 (Figure 7) return the plunger 115 and the check valve 112 in the pilot valve unit to the positions shown in Figure 7. It is apparent that this prevents compressed air from flowing through the pilot valve unit 106 and permits air to be exhausted from the cylinder 104 on the right-hand end of the relay valve unit 86, since the air may flow from the cylinder 104 through conduit 105,

6 throughthe chamber 107 in the housing of pilot valve unit 106, and is exhausted through the tubular plunger 115.

Of course, it is generally desirable that pressure be ap plied to the lap pin 27 prior to the machine being started and, to this end, the surface area of the piston 101 is so small as to permit the valve core to be moved manually by applying pressure to the treadle 97 even though the latch 52 may still be in engagement with the plunger 1150f the pilot valve unit 106. Thus, although fluid pressure is still present in the cylinder 104 under the latter conditions, the core 95 of the relay valve unit 86 may be moved to the position shown in Figure 7 and held in this position until the hand lever 61 is moved tov operative position to release the valve plunger of the pilot valve unit 106. i

In either event, when the valve core 95 of the relay valve unit. 86 occupies the position shown in Figure 7, it isapparent that compressed air then flows from the compressor 122 through conduit 121, through chambers c and d in the body or housing 87 of the relay valve unit 86 and, thence, through the conduits 82, 75 and 76 to admit pressure to the upper ends of the cylinders 65, 66 and to thereby apply pressure to the lap pin 27. In the meantime, air flows from the lower ends of the cylinders 65, 66 through the respective conduits 80, 81, through conduit 84 and through the chambers b and a in the housing 87 of the relay valve unit 86 to be exhausted through the port 124, thus completing a cycle in the operation of the improved lap pin pressure-applying apparatus.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

We claim:

1.? In a ribbon lap machine having a frame, a pair of vertically movable axially spaced bearing blocks mounted in said frame, a lap pin adapted to be removably mounted in said bearing blocks, supporting rolls beneath the lap pin for supporting a lap roll as it is being wound on the lap pin, a starting and stopping mechanism including a latch, a lug normally restraining the latch in operative position, and means carried by at least one of said blocks for engaging said latch to release the same from the lug; means for maintaining uniform pressure on the lap roll throughout its width and diameter and throughout the length of the lap forming the roll comprising a pair of double-acting cylinders spaced above the corresponding bearing blocks and being fixedly supported relative to said frame, a piston in each cylinder, a piston rod fixed to each piston and extending downwardly and being attached to the corresponding bearing block, first and second conduit means connected to the respective upper and lower ends of the cylinders and leading from a source of fluid pressure, a relay valve unit interposed in said conduit means, a pilot valve unit disposed adjacent the latch and having a plunger engageable by said latch when the latch is released from said lug, a movable core in said relay valve unit, manually operable means for moving said core from inoperative to operative position for transmitting fluid pressure from said source to the first conduit means connected to the upper ends of said cylinders for applying downward pressure to the bearing blocks and the lap pin, means responsive to engagement of said plunger of the pilot valve by said latch upon stoppage of the machine for moving said core of the relay valve unit to inoperative position for releasing fluid pressure from the first conduit means and admitting fluid pressure to the second conduit means, means for maintaining constant uniform pressure in the upper ends of both cylinders whenever said core occupies operative position, and said relay valve unit and pilot valve unit being so arranged that said core of the relay valve unit is manually movable to operative positionwhile the plunger of the pilot valve unit is engaged by the latch.

2. In a ribbon lap machine having a frame, a pair of vertically movable axially spaced bearing blocks mounted in "said frame, a lap pin adapted to be removably mounted in said heating blocks, supporting rolls beneath the lap pin for supporting a'lap roll as it is being wound on the lap pin, "a starting and stopping mechanism including a latch, 21 lug normally restraining the latch in operative position, and means carried byone of said blocks for engaging said latch'to release the same from the lug; means for maintaining uniform pressure throughout the length and width of the lap as it is formed into a roll comprising a pair of double-acting cylinders spaced above'the corresponding bearing blocks and being fixedly supported rela tive to said frame, a piston in each cylinder, a piston rod fixed to'each piston and extending "downwardly and being attached to the corresponding bearing block, 'first and second conduit means connected to the respective upper and lower ends of the cylindersand leading from a source of fluid pressure, a relay valve unit interposed in said conduit means, a pilot valveunit disposed adjacent the latch and having a plunger engageable by said latch when the latch is released from said lug, a pressure regulator valve in said conduit means at a point between the source and the relay valve unit, a movable core in said relay valve unit, manually operable means for moving said core from inoperative to operative position for transmitting fiuid pressure from said source to the first conduit means connected to the upper ends of said cylinders for applying downward pressure to the bearing blocks and the lap pin, a relay piston on one end of the core, a relay cylinder in which the relay piston is mounted, means responsive to engagement of the plunger of said pilot valve 'bysaid latch upon stoppage of the machine for admitting fluid pressure into the relay cylinder to move said core of the relay valve unit to inoperative position "for releasing fluid pressure from the first conduit means and admitting fluid pressure to the second conduit means to thereby raise the lap roll away from the supporting rolls, the surface area of said relay piston being such that said core-of the relay valve unit-is manuall-y'movable to operative position while the plunger of the pilot valve unit is 'engaged by the latch.

3. A 'structure according to cl'aim 2 wherein said pilot valve unit is provided with means to exhaust pressure from the relay cylinder when said plunger is released by said latch. v v

4. A structure according to claimB wherein said core is normally resiliently urged to said operative position whereby the core automatically tends to occupy operative position whenever the latch is restrained by the lug.

5. In a ribbon lap machine having a frame, a pair of first and second vertically movable axially spaced hearing blocks mounted in said frame, a lap pin adapted to be removably mountedin said bearing blocks, supporting rolls beneath the lap pin for supporting a lap roll as it is being wound'on the lap pin, and a starting and stopping mechanism; means for maintaining constant equal pressure on both bearing blocks and, thus, on opposite ends of the lap pin comprising first and second double-acting cylinders spaced above the respective first and second bearing blocks and "being fixedly supported relative to said frame, a piston in each cylinder, a piston rod fixed to each piston and extending downwardly and being attached to the corresponding bearing block, first conduit means connecting the upper ends of the cylinders, second conduit means connecting the lower ends of the cylinders, a relay valve unit connected to said first and second conduit means, third conduit means connecting said relay valve unit to a source of fluid pressure, a movable core in said relay valveunit, manually operable means 'for moving sa'id core from inoperative to operative position for transmitting fluid pressure from said source to the first conduit means connectedto the upper ends of said cylinders for applying downward pressureto the bearing blocks and the lap 'pin, a regulator valve in said third conduit means for maintaining constant uniform pressure in said relay valve unit, and means responsive to stoppage of the machine for moving said core of the relay valve unit to inoperative position for releasing fluid pressure from the first conduit means and admitting fluid pressure to 'thesecond conduit means to thereby raise the lap roll away from the supporting rolls, said regulator valve insuring that the pressure on both blocks is equal at all times that said core occupies operative position regardless of the presence of hard places in the lap being wound.

6. In a ribbon lap machine having a frame, a pair of vertically movable axially spaced bearing blocks mounted in said frame, a lap pin adapted to be removably mounted in said bearing blocks, supporting rolls beneath the lap pin for supporting a lap roll as it is being wound on the lap pin, a starting and stopping mechanism including a latch, a lug normally restraining the latch in operative position, and means carried by at least one of said blocks for engaging said latch to release the same from the lug; means for maintaining constant equal pressure on both bearing blocks and, thus, on opposite ends of the lap pin comprising a double-acting cylinder spaced above each ofthe bearing blocks and being fixedly supported relative to said frame, a piston in each cylinder, a piston rod fixed to each piston and extending downwardly and being attached to the corresponding bearing block, first and second conduit means connected to the respective upper and lower ends of the cylinders and thereby establishing communication between the upper ends of the cylinders and establishing communication between the lower ends of the cylinders, a relay valve unit for alternatively directing fluid pressure to said first and second conduit means, a pilot valve unit disposed adjacent the latch and having a plunger engageable by said latch when the latch is released from said lug, a

movable core in said relay valve unit, a third conduit means connecting said relay valve unit to a source of fluid pressure, regulator means for maintaining a constant uniform pressure in said third conduit mean, manually operable means for moving said core from inoperative to operative position for transmitting fluid pressure from said source to the first conduit means for applying uniform downward pressure to the bearing blocks and the lap pin, means responsive to engagement-of said plunger of the pilot valve by said latch upon stoppage of the machine for moving said core of the relay valve unit to inoperative position for releasing fluid pressure from the first conduit means and admitting fluid pressure to the second conduit means, and said relay valve unit and pilot valve unit being so arranged that said core of the relay valve unit is manually movable to operative position while theplunger of the pilot valve unit is engaged by the latch.

References Cited in the file of this patent UNITED STATES PATENTS 2,573,938 Tyler et al. Nov. 6, 1951 2,678,172 Curley May 11, 1954 2,682,998 Strassler July 6, 1954 2,715,913 Taylor Aug. 23, 1955 

